3D solar towers offer 20x more power output
Researchers at MIT have created 3D solar towers that are said to give a power output of up to 20x that of fixed flat panels with the same base area.
The team's approach, based on both computer modelling and outdoor testing of real modules, involved extending the solar cells upwards in a three dimensional tower or cube configuration to enable them to better capture the sun's rays.
"I think this concept could become an important part of the future of photovoltaics," said Jeffrey Grossman, an associate professor of Power Engineering at MIT.
The researchers initially used a computer algorithm to explore a variety of possible configurations, and developed analytic software capable of testing any given configuration under a range of latitudes, seasons and weather.
Then, to confirm their model's predictions, they built and tested three different arrangements of solar cells on the roof of an MIT laboratory building for several weeks.
Although more expensive to produce than traditional flat panels, the 3D models were said to demonstrate a much more uniform power output over the course of a day. This, according to the researchers, was due to the fact the 3D structures' vertical surfaces can collect much more sunlight during mornings, evenings and winters, when the sun is closer to the horizon.
"The time is ripe for such an innovation because solar cells have become less expensive than accompanying support structures, wiring and installation," noted Grossman. "As the cost of the cells themselves continues to decline more quickly than these other costs, the advantages of 3D systems will grow accordingly."
Although computer modelling by Grossman and his colleagues showed that the biggest advantage would come from complex shapes, such as a cube where each face is dimpled inward, these were found to be too difficult to manufacture.
The team's next step is to study a collection of 3D towers rather than individual structures, accounting for the shadows that one tower would cast on others at different times of day.
"Even 10 years ago, this idea wouldn't have been economically justified because the modules cost so much," Grossman concluded. "But now, the cost for silicon cells is a fraction of the total cost, a trend that will continue downward in the near future."
